1. Field of the Invention
The present invention relates to new dentifrice cleaning and polishing agents and to the formulation and utilization of dentifrice preparations incorporating such cleaning and polishing agents. In particular, the invention relates to a dentifrice cleaning and polishing composition comprising purified, calcined kaolin particles predominantly of the gamma alumina and/or mullite form, not more than a minor amount of titanium-containing impurities being present and the particles being at least predominantly less than about 10 microns in diameter.
These compositions serve to clean and polish dental hard tissue in a novel manner such that reaccumulations of pellicle and materia alba and occurrence and reformation of calculus on oral hard tissue are markedly reduced, thereby significantly reducing the occurrence of gingivitis and other soft tissue and periodontal disease. Fluoride-containing anticariogenicadjuvants such as sodium fluoride, NaF, may also usefully be incorporated in such compositions.
2. Description of the Prior Art
Dental research has developed substantial evidence that beyond the age of thirty-five years loss of teeth is predominantly the result of periodontal involvement rather than dental caries. However, evidence in the literature suggests that gingivitis itself may be present in a large portion of the population at a much earlier age. In this form the disease is reversible. A major factor contributing to periodontal disease is the accumulation of certain forms of dental plaque and calculus (e.g., salivary tartar) on the teeth. These accumulations result in tissue inflammation of the surrounding gingiva, and, as the condition increases in severity, the periodontal fibers and supporting bone subsequently become affected. These reactions lead to the destruction of the supporting structures and the subsequent mass loss, in most instances, of sound teeth.
Heretofore, commercially available dentifrices containing abrasives such as insoluble sodium metaphosphate (NaPO.sub.3) calcium hydrogen phosphate dihydrate/anhydrous calcium hydrogen phosphate, (CaHPO.sub.4. 2H.sub.2 O/CaHPO.sub.4), calcium pyrophosphate (Ca.sub.2 P2O.sub.7), and silica (SiO.sub.2) have exhibited relatively unsatisfactory enamel-polishing qualities and consequently have not been wholly effective in preventing the reaccumulation of materia alba, oral debris, plaque, pellicle, exogenous stains, and dental calculus. In particular, while conventional cleaning and polishing agents used with a toothbrush are capable, to varying degrees, of removing materia alba, food particles, exogenous stains, and other tooth surface pigmentations when utilized in ordinary daily brushings, they have not exhibited the ability to remove the more resistant forms of enamel pigments and to produce a smooth tooth surface resistant to dental calculus reformation. Furthermore, these conventional abrasives leave the teeth esthetically less desirable than would more effective polishing agents.
In an attempt to improve enamel-polishing qualities and cleaning efficiency, some commercial dentifrices now contain abrasive materials, such as alumina (Al.sub.2 O.sub.3), which have been reported to impart a high polish to dental enamel when a low particle size is employed (100 percent less than 0.5 microns in alpha alumina). However, such materials do not clean enamel effectively without excessively abrading the dental hard tissue (i.e., enamel and dentin).
The benficial effects, in terms of a reduction in the incidence of dental caries, resulting from the incorporation of water-soluble fluoride salts, such as sodium fluoride, are well known. However, efforts to utilize such salts in dentifrices suitable for home use have been handicapped by the tendency for fluoride ions to be deactivated and rendered unavailable by other ingredients, particularly the abrasive component of such dentifrices. While generally speaking, dentifrice abrasives in therapeutic products used today are to varying degrees compatible with fluoride agents, there is a wide variation in compatibility. Calcium-containing abrasives are not particularly compatible. While the non-calcium-containing abrasives are somewhat more compatible, they frequently are inferior with regard to enamel polishing.
For example, Cooley et al. U.S. Pat. No. 3,070,510 teaches the use of substantially water-impervious, cross-linked, thermosetting, highly-polymerized resins as dentifrice cleaning and polishing agents. Although resin agents of the type disclosed in the Cooley et al. patent exhibit improved fluoride ion compatibility relative calcium calcium pyrophosphate, these agents similarly do not provide satisfactory cleaning and polishing characteristics.
Saul et al. U.S. Pat. No. 3,105,013 recommends using calcined aluminum silicate as a dental abrasive on the basis of its compatibility with fluoride adjuvants. However, the preferred material of the Saul et al. patent, "Kaopolite SF", as commercially available is an off-white color and is thus esthetically undesirable in a commercial dentifrice.
Japanese Pat. No. 24224/74 describes dental abrasives combining calcined kaolins with other abrasives such as calcium carbonate, calcium hydrogen phosphate dihydrate, and the like. The Japanese patent teaches nothing concerning the purification of the kaolin, and it specifically states that the use of calcined kaolin alone as a dental abrasive is undesirable.
Thus, prior art materials intended for use as cleaning and polishing constituents of dentifrice preparations have been unsatisfactory in one or more of the following respects, namely, relatively poor cleaning and polishing performances (especially with respect to prevention of reaccumulation of dental calculus, pellicle, materia alba, and the more resistant forms of oral hard tissue stains and pigmentations), incompatibility with fluoride-containing anticariogenic agents, and adverse abrasion.